AndroidJavaClass jc_unityPlayer = new AndroidJavaClass("com.unity3d.player.UnityPlayer");
AndroidJavaObject jo_Activity = jc_unityPlayer.GetStatic<AndroidJavaObject>("currentActivity");
// get android.accounts.AccountManager and call android.accounts.AccountManager.getAccountsByType
AndroidJavaClass jc_AccountManager = new AndroidJavaClass("android.accounts.AccountManager");
AndroidJavaObject jo_AccountManager = jc_AccountManager.CallStatic<AndroidJavaObject>("get", jo_Activity);
AndroidJavaObject jo_Accounts = jo_AccountManager.Call<AndroidJavaObject>("getAccountsByType", "com.google");
// convert java accounts into array
AndroidJavaObject[] jo_AccountsArr = AndroidJNIHelper.ConvertFromJNIArray<AndroidJavaObject[]>(jo_Accounts.GetRawObject());
if (jo_AccountsArr.Length > 0) LoginTxt.GetComponent<Text>().text = "Login: " + jo_AccountsArr[0].Get<string>("name");